1. Field of the Invention
The present invention relates to a display device. In particular, the present invention relates to a display device capable of performing 3D display.
2. Description of the Related Art
Display devices are widely used, ranging from large display devices such as television devices to small display devices such as mobile phones. The display devices each include a display portion in which a plurality of pixels are provided in matrix. Desired color display is performed in each pixel, so that an image is formed in the display portion. In recent years, display devices capable of performing 3D display have been developed.
As systems for performing 3D display, there are a system (a glasses system) in which a period of display for a left eye and a period of display for a right eye are distinguished from each other in a display portion and a user wears glasses so that the left eye sees the former display and the right eye sees the latter display, and a system (hereinafter, an autostereoscopic system) in which a pixel for display for a left eye and a pixel for display for a right eye are distinguished from each other in a display portion and a structure (e.g., a parallax barrier) which allows the left eye to see the former display and the right eye to see the latter display is employed.
It is not necessary to prepare glasses to see autostereoscopic 3D images, which offers a high convenience. However, in the case where a display device performing 3D display by an autostereoscopic system performs 2D display, the resolution is decreased due to a unique structure (e.g., a parallax barrier) of an autostereoscopic system.
In Patent Document 1, a display device is disclosed in which a decrease in 2D display resolution of the display device which performs 3D display by an autostereoscopic system can be prevented. Specifically, in the display device disclosed in Patent Document 1, a parallax barrier is formed using liquid crystal whose alignment state is controlled by an applied voltage. Thus, in the display device, whether a parallax barrier is provided or not can be selected. In other words, the display device can perform 3D display in a state where a parallax barrier is provided and perform 2D display in a state where a parallax barrier is not provided.